Allow ClassPathResources to be filtered by FilteredClassLoader

See gh-14774

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/context/FilteredClassLoader.java

@@ -20,12 +20,15 @@ import java.net.URL;
 import java.net.URLClassLoader;
 import java.util.function.Predicate;
 
+import org.springframework.core.io.ClassPathResource;
+
 /**
- * Test {@link URLClassLoader} that can filter the classes it can load.
+ * Test {@link URLClassLoader} that can filter the classes and resources it can load.
  *
  * @author Andy Wilkinson
  * @author Stephane Nicoll
  * @author Phillip Webb
+ * @author Roy Jacobs
  * @since 2.0.0
  */
 public class FilteredClassLoader extends URLClassLoader {
@@ -48,10 +51,19 @@ public class FilteredClassLoader extends URLClassLoader {
 		this(PackageFilter.of(hiddenPackages));
 	}
 
+	/**
+	 * Create a {@link FilteredClassLoader} that hides resources from the given packages.
+	 * @param hiddenResources the resources to hide
+	 */
+	public FilteredClassLoader(ClassPathResource... hiddenResources) {
+		this(ClassPathResourceFilter.of(hiddenResources));
+	}
+
 	/**
 	 * Create a {@link FilteredClassLoader} that filters based on the given predicate.
-	 * @param filters a set of filters to determine when a class name should be hidden. A
-	 * {@link Predicate#test(Object) result} of {@code true} indicates a filtered class.
+	 * @param filters a set of filters to determine when a class name or resource should
+	 * be hidden. A {@link Predicate#test(Object) result} of {@code true} indicates a
+	 * filtered class or resource.
 	 */
 	@SafeVarargs
 	public FilteredClassLoader(Predicate<String>... filters) {
@@ -70,6 +82,16 @@ public class FilteredClassLoader extends URLClassLoader {
 		return super.loadClass(name, resolve);
 	}
 
+	@Override
+	public URL getResource(String name) {
+		for (Predicate<String> filter : this.filters) {
+			if (filter.test(name)) {
+				return null;
+			}
+		}
+		return super.getResource(name);
+	}
+
 	/**
 	 * Filter to restrict the classes that can be loaded.
 	 */
@@ -124,4 +146,32 @@ public class FilteredClassLoader extends URLClassLoader {
 
 	}
 
+	/**
+	 * Filter to restrict the resources that can be loaded.
+	 */
+	public static final class ClassPathResourceFilter implements Predicate<String> {
+
+		private final ClassPathResource[] hiddenResources;
+
+		private ClassPathResourceFilter(ClassPathResource[] hiddenResources) {
+			this.hiddenResources = hiddenResources;
+		}
+
+		@Override
+		public boolean test(String resourceName) {
+			for (ClassPathResource hiddenResource : this.hiddenResources) {
+				if (hiddenResource.getFilename() != null
+						&& resourceName.equals(hiddenResource.getPath())) {
+					return true;
+				}
+			}
+			return false;
+		}
+
+		public static ClassPathResourceFilter of(ClassPathResource... hiddenResources) {
+			return new ClassPathResourceFilter(hiddenResources);
+		}
+
+	}
+
 }

spring-boot-project/spring-boot-test/src/test/java/org/springframework/boot/test/context/FilteredClassLoaderTests.java

@@ -16,8 +16,12 @@
 
 package org.springframework.boot.test.context;
 
+import java.net.URL;
+
 import org.junit.Test;
 
+import org.springframework.core.io.ClassPathResource;
+
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 
@@ -25,9 +29,13 @@ import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
  * Tests for {@link FilteredClassLoader}.
  *
  * @author Phillip Webb
+ * @author Roy Jacobs
  */
 public class FilteredClassLoaderTests {
 
+	private static ClassPathResource TEST_RESOURCE = new ClassPathResource(
+			"org/springframework/boot/test/context/FilteredClassLoaderTestResource.txt");
+
 	@Test
 	public void loadClassWhenFilteredOnPackageShouldThrowClassNotFound()
 			throws Exception {
@@ -55,4 +63,22 @@ public class FilteredClassLoaderTests {
 		classLoader.close();
 	}
 
+	@Test
+	public void loadResourceWhenFilteredOnResourceShouldReturnNotFound()
+			throws Exception {
+		try (FilteredClassLoader classLoader = new FilteredClassLoader(TEST_RESOURCE)) {
+			final URL loaded = classLoader.getResource(TEST_RESOURCE.getPath());
+			assertThat(loaded).isNull();
+		}
+	}
+
+	@Test
+	public void loadResourceWhenNotFilteredShouldLoadResource() throws Exception {
+		try (FilteredClassLoader classLoader = new FilteredClassLoader(
+				(resourceName) -> false)) {
+			final URL loaded = classLoader.getResource(TEST_RESOURCE.getPath());
+			assertThat(loaded).isNotNull();
+		}
+	}
+
 }

spring-boot-project/spring-boot-test/src/test/resources/org/springframework/boot/test/context/FilteredClassLoaderTestResource.txt

@@ -0,0 +1 @@
+Used by FilteredClassLoaderTests.java